High pressure pump

Abstract

A housing-includes a pressurizing chamber. A plunger is moved to increase and decrease a volume of the pressurizing chamber, so that the plunger can pressurize the fuel in the pressurizing chamber. A fuel chamber forming portion is placed on a radially outer side of the plunger and forms a fuel chamber that is communicated with the pressurizing chamber. A pulsation damper is placed in an inside of the fuel chamber and is operable to reduce pressure pulsation of the fuel in the fuel chamber. Fixable portions are placed on a radially outer side of the plunger while each of the fixable portions includes a receiving through-hole. The fixable portions are fixed to an engine with bolts, which are provided to correspond with the receiving through-holes, respectively. The fuel chamber forming portion is displaced from axes of the receiving through-holes.

The invention claimed is: 
     
       1. A high pressure pump configured to be installed to an internal combustion engine to pressurize, discharge and supply fuel to the internal combustion engine, the high pressure pump comprising:
 a housing that includes a pressurizing chamber; 
 a plunger that is movable in such a manner that the plunger increases and decreases a volume of the pressurizing chamber upon movement of the plunger, and thereby the plunger is operable to pressurize the fuel in the pressurizing chamber; 
 a fuel chamber forming portion that is placed on a radially outer side of the plunger and forms a fuel chamber that is communicated with the pressurizing chamber, wherein the fuel chamber forming portion includes a casing, which forms the fuel chamber at an inside of the casing while the casing is formed separately from the housing and is installed to an outer peripheral wall of the housing, and the fuel chamber is defined between one wall portion and another wall portion of the casing in a radial direction of an axis of the plunger; 
 a pulsation damper that is placed in an inside of the fuel chamber of the casing and is operable to reduce pressure pulsation of the fuel in the fuel chamber, wherein the pulsation damper is held between the one wall portion and the another wall portion of the casing in the radial direction; 
 a discharge portion that discharges the fuel, which is pressurized in the pressurizing chamber; and 
 a fixable portion that is placed on the radially outer side of the plunger and includes a receiving through-hole while the fixable portion is configured to be fixed to the internal combustion engine with a fixing member that is formed to correspond with the receiving through-hole, wherein: 
 the fuel chamber forming portion is placed at a location that is displaced from an axis of the receiving through-hole; 
 the casing, the fixable portion and the discharge portion are entirely placed on an inner side of an imaginary cylindrical surface that circumferentially extends about the axis of the plunger along an end part of the discharge portion; and 
 the fixable portion is configured to be directly fixed to an engine head of the internal combustion engine with the fixing member. 
 
     
     
       2. The high pressure pump according to  claim 1 , wherein the casing is placed at the location that is displaced from an imaginary tubular surface that includes all of an inner wall of the receiving through-hole. 
     
     
       3. The high pressure pump according to  claim 1 , wherein the fixable portion is fixable to the internal combustion engine through the fixing member when the fixing member is inserted through the receiving through-hole and is fixed to the internal combustion engine, or when the fixing member is fixed to a portion of the internal combustion engine, which is inserted through the receiving through-hole. 
     
     
       4. The high pressure pump according to  claim 1 , wherein the pulsation damper is shaped into a hollow circular disk form and is placed such that an axis of the pulsation damper intersects with the axis of the plunger, or the axis of the pulsation damper is skew to the axis of the plunger. 
     
     
       5. The high pressure pump according to  claim 4 , wherein the pulsation damper is placed such that the axis of the pulsation damper is perpendicular to the axis of the plunger or is skew to the axis of the plunger at a right angle. 
     
     
       6. The high pressure pump according to  claim 1 , wherein the receiving through-hole is one of a plurality of receiving through-holes that are symmetrical to each other with respect to the axis of the plunger, which serves as an axis of symmetry. 
     
     
       7. The high pressure pump according to  claim 6 , wherein the casing is shaped into a hollow circular disk form and has an outer diameter that is larger than a distance between the plurality of receiving through-holes. 
     
     
       8. The high pressure pump according to  claim 1 , further comprising an inlet portion that is shaped into a tubular form while the inlet portion is communicated with the fuel chamber and guides the fuel from an outside to the fuel chamber, wherein the inlet portion is joined to the casing. 
     
     
       9. The high pressure pump according to  claim 1 , further comprising an inlet portion that is shaped into a tubular form while the inlet portion is communicated with the pressurizing chamber and guides the fuel from an outside to the fuel chamber, wherein the inlet portion is joined to the housing. 
     
     
       10. The high pressure pump according to  claim 8 , wherein the inlet portion is placed at a location that is displaced from the axis of the receiving through-hole. 
     
     
       11. The high pressure pump according to  claim 1 , further comprising a relief valve device that is operable to release the fuel in the discharge portion toward the pressurizing chamber side of the discharge portion when a pressure of the fuel in the discharge portion becomes equal to or larger than a predetermined value, wherein the relief valve device is placed at a location that is displaced from the axis of the receiving through-hole. 
     
     
       12. The high pressure pump according to  claim 1 , further comprising:
 a suction valve device that is operable to open and close a connection between the pressurizing chamber and the fuel chamber; and 
 an electromagnetic drive device that is operable upon energization of the electromagnetic drive device to drive the suction valve device to open or close the connection between the pressurizing chamber and the fuel chamber, wherein the electromagnetic drive device is placed at a location that is displaced from the axis of the receiving through-hole. 
 
     
     
       13. The high pressure pump according to  claim 12 , wherein the electromagnetic drive device is placed along the axis of the plunger. 
     
     
       14. The high pressure pump according to  claim 12 , wherein the electromagnetic drive device is placed on the radially outer side of the plunger. 
     
     
       15. The high pressure pump according to  claim 12 , wherein:
 the electromagnetic drive device includes a connector, to which a harness for supplying an electric power is connectable; and 
 the connector is placed at a location that is displaced from the axis of the receiving through-hole. 
 
     
     
       16. A high pressure pump configured to be installed to an internal combustion engine to pressurize, discharge and supply fuel to the internal combustion engine, the high pressure pump comprising:
 a housing that includes a pressurizing chamber; 
 a plunger that is movable in such a manner that the plunger increases and decreases a volume of the pressurizing chamber upon movement of the plunger, and thereby the plunger is operable to pressurize the fuel in the pressurizing chamber; 
 a fuel chamber forming portion that is placed on a radially outer side of the plunger and forms a fuel chamber that is communicated with the pressurizing chamber, wherein the fuel chamber forming portion includes a casing, which forms the fuel chamber at an inside of the casing while the casing is formed separately from the housing and is installed to an outer peripheral wall of the housing, and the fuel chamber is defined between one wall portion and another wall portion of the casing in a radial direction of an axis of the plunger; 
 a pulsation damper that is placed in an inside of the fuel chamber of the casing and is operable to reduce pressure pulsation of the fuel in the fuel chamber, wherein the pulsation damper is held between the one wall portion and the another wall portion of the casing in the radial direction; 
 a discharge portion that discharges the fuel, which is pressurized in the pressurizing chamber; and 
 a fixable portion that is placed on the radially outer side of the plunger and includes a receiving through-hole while the fixable portion is configured to be fixed to the internal combustion engine with a fixing member that is formed to correspond with the receiving through-hole, wherein: 
 the casing is placed at a location that is displaced from an axis of the receiving through-hole; 
 a portion of the casing, an entirety of the fixable portion and an entirety of the discharge portion are placed on an inner side of an imaginary cylindrical surface that circumferentially extends about the axis of the plunger along an end part of the discharge portion; 
 another portion of the casing is placed on an outer side of the imaginary cylindrical surface; and 
 the fixable portion is configured to be directly fixed to an engine head of the internal combustion engine with the fixing member. 
 
     
     
       17. The high pressure pump according to  claim 1 , further comprising a bolt inserted through the receiving through-hole of the fixable portion and into a fixation hole of the engine head of the internal combustion engine.